Inflatable air cells have been used in a variety of configurations to provide adjustments to the contour of a seat and in this manner enhance the comfort of the individual using the seat. This is especially important in automobiles where long periods of driving can cause pain and distraction or in other seating applications where individuals are sedentary for long periods of time.
The seating system described in U.S. Pat. No. 4,915,124 involves a simple system of multiple air cells in which each cell is connected through a valve to a source of pressurized air in a manner which allows for simultaneous inflation or deflation of the cells in response to a manually operated switch.
Another air cell inflation system is shown in U.S. Pat. No. 5,263,765. This device inflates the air cells according to two predetermined modes, through tubes individually controlled by valves which are in turn controlled by a microcomputer. The microcomputer is responsive to the fatigue of the driver as represented by seat belt displacement.
The air cells of U.S. Pat. No. 4,722,550 are adjusted in response to engine speed or steering angle and allows for selective inflation between two zones of air cells, one at the sides and one for the bottom and back of the seat. One valve controls each of the zones and is actuated by a microcomputer which receives sensed signals relative to the operating parameters of the automobile.
A manually operated power control system for a lumbar cushion is described in U.S. Pat. No. 4,707,027. A complex seating mechanism is devised to allow the operator to inflate and deflate the cushion while sensing pressure in the cushion to limit actuation of the system to prevent damage thereto.
U.S. Pat. No. 4,833,614 shows a system by which an air cell can be inflated to a selected pressure by sensing the actual pressure, comparing it to the pressure selected and then adjusting the air supply to inflate or deflate the air cell to the selected pressure. In this case the microcomputer converts the pressure signal it receives to a time based signal relative to the period necessary to run the pump to obtain the selected pressure. The pressure is sensed directly from sensors within the air support.
The above systems are limited either to narrow preset operational boundaries if responsive to vehicle operation or occupant movement or rely on the operator to provide a manual interactive response. Although each attempts to improve the comfort of the user and adjust in some manner to the variety of shapes and sizes of the user, each falls short because of the inherent limitations in the particular system.
In addition to inflatable air cells that have been used as a means to actuate adjustment mechanisms for altering the contour of a seat for many years, other adjustment is desirable to customize the seat contour to a particular user. In applications such as automobile seating where fatigue may become a factor, it is of particular interest to provide adjustment from user to user and during use by an individual. Air cells have also been used to adjust the tactile support for such critical regions as the lumbar portion of the back that is particularly susceptible to fatigue. In this instance the air cell provides direct support and not just an adjustment mechanism.
An air cell adjustment mechanism of such tactile support systems is shown in U.S. Pat. No. 5,137,329. This patent describes a support structure consisting of front and back plates between which are sandwiched two air cells. The air cells may be selectively inflated and deflated to provide pivoting adjustment motion to the front plate that provides the support contour for the seat back.
Tactile adjustment is provided by the air cell of U.S. Pat. No. 4,807,931 which is also mounted in a seat to provide the support contour for directly engaging the lumbar region of the user's back.
In addition to the aforesaid systems other vehicle seating systems having included an array of air cells in the seat back or as part of the head rest with the air cells being selectively inflated to control the contour of these parts of the seating system for comfort considerations. Examples of such systems are shown in U.S. Pat. Nos. 4,720,146; 4,840,425; 5,135,282; 5,558,398 and 5,772,281.
In addition to the aforesaid vehicle seating systems it is known in the prior art to provide acceleration responsive inflatable air cells to aid in positioning a seat occupant within the seat structure. One example of such an arrangement is shown in U.S. Pat. No. 4,634,083 wherein an acceleration signal will control an air cell array in a helicopter seat to isolate the occupant from helicopter vibrations. U.S. Pat. No. 5,427,331 discloses an aircraft ejection system that upon sensing ejection will rapidly deflate a pneumatic cushion to assure that the occupant is seated against a firm seat surface as the rapid acceleration of seat against occupant occurs so as to avoid spinal injury. U.S. Pat. No. 5,707,109 discloses a vehicle seat that has inflatable side bolsters that are inflated in response to lateral vehicle acceleration to provide additional occupant side support during vehicle turns.
While suitable for their intended purpose, the various known vehicle seat systems with inflatable air cells for contour shaping of the vehicle seat surface to enhance comfort do not provide for air cell pressure control in response to vehicle impact that can cause the occupant to slam against a seat back and head rest structure following vehicle impact. In seating structures without air cells, such movement can cause the occupant to be in contact with hard seating structure or the hard mechanical components of metallic lumbar support systems.